As organic EL panels using an organic EL device, a panel in which the organic EL device is formed by successively laminating a first electrode comprising ITO (Indium Tin Oxide) or the like as an anode, an organic layer having at least a luminescent layer, and a non-light-transmitting second electrode comprising aluminum (Al) or the like as a cathode, on a light-transmitting supporting substrate comprising a glass material is known (see, for example, Patent Document 1).
Such an organic EL panel emits light by injecting holes from the first electrode, injecting electrons from the second electrode, and rebonding the holes and electrons in the luminescent layer, and a long-lived panel that emits light with a given luminance over a long period of time is desired.    Patent Document 1: JP-A-59-194393